The function of the fuel filter is to filter the harmful impurities and moisture in the fuel system, so as to guarantee the normal operation of the engine, reduce wear, prevent congestion, and improve the lifetime of the engine. In the prior art, after the fuel filter has been used for a certain period, impurities in the fuel will jam the filtering material in the filter, leading to the degradation of the filtering performance of the filtering material. Thus, regular replacement is necessary. Since the replaced fuel filter cannot be recycled, massive waste is caused. Moreover, residual fuel and filtered dirt in the fuel filter will contaminate the environment.